Random Little Question Thread
#1683
11-07-2010, 10:31 PM
how old are the springs? As they settle you might get a bit more neg camber... you're arent excessively out of spec, but as time goes on it might get more so... are the $200 a-arms you mentioned SPC? (used I presume)... btw, my understanding is cross caster is the important spec, and yours seems to be good.
Springs have been on about a month and had several hundred miles on them before I was able to have the alignment done. They seem to have settled about as much as they're going to.
No, I don't have a line on any used a-arms at the moment. I misspoke about the "couple hundred" thinking I'd seen vendors asking upper 200's for them. Looking again upper 300's seems more realistic.
#1686
11-08-2010, 03:32 PM
#1687
11-08-2010, 03:34 PM
Mike, if it helps any. I was at approx -2.4 degrees camber in the front with a 9.5 +3. When I threw on a 15mm spacer I had to dial in -4.7 camber and it poked out a couple mm more. 2.3 degrees got me maybe 17-18 mm further out (15mm plus whatever extra it got pushed out). For the rear I'm unsure.
#1688
11-08-2010, 03:40 PM
Mike, I totally understand the question, I'm just not 100% sure on the ratio of mm to camber either. I thought it was 5mm ~ 1 degree of camber, but I'm not sure. I'll ask the guys in the stretched/aggressive thread, I'm sure they can give me an answer. Once we have that ratio we will be able to calculate everything. Need to know your tire sizes too, I assume 245/35, 275/35 (or 30 series).
#1690
11-08-2010, 10:36 PM
#1691
11-08-2010, 11:47 PM
Mike I talked to Grant tonight he said assume 1 degree of camber is 5-7mm.
Dave also confirmed this via math:
Given that you don't want to run much neg camber, like you said, you may need to look for slightly higher offsets.
Dave also confirmed this via math:
pretty much, use a trig formula with a right angle triangle. I created a formula for you to use...
In this pic, visualize your wheel well. The angle is front the center point of your wheel. The angle (theta) will be the degree change in your camber setting. Side CB (adjacent side) will be your wheel + tire height. Side AB will be your clearance (opposite side)
remember: tan(angle theta) = opposite side(AB)/adjacent side(CB)
therefore: to figure out opposite side length (AB) you must have the following algabraic formula:
tan(angle theta) x adjacent side (CB) = opposite side (AB)
tan(theta)xCB = AB
theta = tan(1*) = .0175
CB = Sidewall height (mm) + (Wheel diameter in mm/2) {note 1in = 25.4mm)
AB = clearance (mm)
theta(CB) = AB
Here is what I ran for my car today. Running a 255/35/19 rear
Sidewall height = 255(.35) = 89.25mm
Wheel Diameter = 19"(25.4) = 482.6mm/2 = 241.3mm (radius)
CB = 89.25+241.3 = 330.5mm
.0175(330.55) = 5.78mm overall change in clearance from the fender line w/ a 1* change in camber (+ or -)
In this pic, visualize your wheel well. The angle is front the center point of your wheel. The angle (theta) will be the degree change in your camber setting. Side CB (adjacent side) will be your wheel + tire height. Side AB will be your clearance (opposite side)
remember: tan(angle theta) = opposite side(AB)/adjacent side(CB)
therefore: to figure out opposite side length (AB) you must have the following algabraic formula:
tan(angle theta) x adjacent side (CB) = opposite side (AB)
tan(theta)xCB = AB
theta = tan(1*) = .0175
CB = Sidewall height (mm) + (Wheel diameter in mm/2) {note 1in = 25.4mm)
AB = clearance (mm)
theta(CB) = AB
Here is what I ran for my car today. Running a 255/35/19 rear
Sidewall height = 255(.35) = 89.25mm
Wheel Diameter = 19"(25.4) = 482.6mm/2 = 241.3mm (radius)
CB = 89.25+241.3 = 330.5mm
.0175(330.55) = 5.78mm overall change in clearance from the fender line w/ a 1* change in camber (+ or -)
#1692
11-08-2010, 11:57 PM
Thanks Marcus, much appreciated! I would need to study the formula much longer to grasp the principal (hated it in school, and still not warm & fuzzy about it 
) - but the original suggesting of 6mm/1* apparently is right.
It's looking like finding the right offset (reasonably lightweight) wheel used isn't gonna happen on the G or Z forums... Flaring the fenders presented a predicament that I didn't think would be this challenging.
There is an awesome wheel that comes in perfect specs (size/offset/weight) but is 3600-4200
I was trying to avoid that but alas the spending remains inevitable for the ideas I have with this car.
I really need an NSX
BTW, what thread is the post you copied? *edit - nvrmnd, I clinked the arrow and it took me to thread
) - but the original suggesting of 6mm/1* apparently is right. It's looking like finding the right offset (reasonably lightweight) wheel used isn't gonna happen on the G or Z forums... Flaring the fenders presented a predicament that I didn't think would be this challenging.
There is an awesome wheel that comes in perfect specs (size/offset/weight) but is 3600-4200
I was trying to avoid that but alas the spending remains inevitable for the ideas I have with this car.I really need an NSX
BTW, what thread is the post you copied? *edit - nvrmnd, I clinked the arrow and it took me to thread
#1693
11-09-2010, 07:38 PM
#1694
11-09-2010, 08:28 PM